Degenerative Disorders Flashcards

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1
Q

Donepezil

A

Centrally acting cholinesterase inhibitor

Alzheimers

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2
Q

Rivastigmine

A

Centrally acting cholinesterase inhibitor

Alzheimers

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3
Q

Galantamine

A

Centrally acting cholinesterase inhibitor

Alzheimers

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4
Q

Memantine

A

NMDA Channel blocker

Slows disease progression in Alzheimer’s

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5
Q

Levodopa

A

Restores DA levels in the basal ganglia by entering CNS via amino acid transporters. Decarboxylated to DA in cells expressing L-AAAD.

  • 2% gets into the brain; co-administer with carbidopa=L-AAAD inhibitor that doesn’t cross BBB (Increases dose in CNS and peripheral side effects).
  • Can also be co-administered with COMT inhibitor=entacapone.
  • Very short half life; absorption depends on GI contents (amino acid transporters that are responsible for uptake can be saturated with high protein meal).
  • Effectiveness lost after 1st few years of treatment
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6
Q

Levodopa–side effects

A
  • CNS side effects: aren’t alleviated by carbidopa. Dyskinesia, Dementia, confusion
  • Peripheral side effects: reduced by carbidopa. Nausea, Postural hypotension, Arrhythmias, HTN
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7
Q

Levodopa–drug interactions

A
  • Pyridoxine; increases peripheral DA metabolism
  • MAO inhibitors: HTN (except selegiline)
  • Halothane: arrhythmia
  • Antipsychotics that are DA Receptor antagonists
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8
Q

Levodopa–containdications

A
  • Glaucoma
  • Psychosis
  • Cardiac disease with arrhythmia
  • Malignant melanoma
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9
Q

DA Receptor Agonists

A
  • Mimic dopamine without need for intact nerve terminals. Mechanism: DA receptor agonists in striatum.
  • Advantages: Receptor subtype selectivity, longer T1/2, less DA-dependent oxidative stress?
  • Firstline: longer duration, reduce DA synthesis so less oxidative toxicity. Initial therapy in young patients.
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10
Q

Pramipexole and Ropinerole

A

D2 Receptor Agonists

Most commonly used

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11
Q

Apomorphine

A
  • High affinity D4 agonist; moderate for D2/3/5
  • Subcutaneous injection for immediate therapy of an “off” episode
  • Reserved for patients who are refractory to other treatments
  • Side effects: Increased QT prolongation and injection site reaction
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12
Q

DA Receptor Agonists Side Effects

A
  • Nausea
  • Fatigue
  • Daytime sleepiness
  • CNS toxicity: confusion (worse than L-Dopa), dyskinesia (better than with L-Dopa)
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13
Q

MAO Inhibitors

A
  • Need to be careful…in liver, MAO-A metabolizes tyramine, which is a sympathomimetic.
  • MAO-B=major form in the brain
  • MAO inhibition prolonges action of dopamine and reduces oxidative stress on neurons
  • Mechanism: selective, irreversible inhibition of MAO-B.
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14
Q

Selegiline and Rasagiline

A
  • MAO-B inhibitors
  • Prescribed as soon as disease is diagnosed; benefit is modest
  • advanced disease: combined with L-Dopa to prolong its half life
  • Anti-depressant
  • Side effects: can worsen side effects of L-dopa, and is metabolized to amphetamine/methamphetamine–causes anxiety and insomnia.
  • When administered with TCAs or SSRIs can lead to Serotonin Syndrome (stupor, rigidity, agitation, hyperthermia)
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15
Q

Tolcapone, Entacapone

A
  • COMT metabolizes DA; inhibition prolongs DA action and decreases L-Dopa metabolism to non-DA metabolites
  • Tolcapone: long T1/2 and inhibits both peripheral and central COMT
  • Entacapone: short T1/2 and does not penetrate CNS well; usually co-administered with L-Dopa to eliminate peripheral metabolism.
  • Side Effects: nausea, orthostatic hypotension, vivid dreams, confusion, hallucinations
  • Tolcapone can cause liver toxicity–not used except as last resort
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16
Q

Trihexyphenidyl and Benztropine

A
  • Antagonists of striatal muscarinic receptors; blunt overactivity of cholinergic interneurons in striatum that are uninhibited by loss of dopamine.
  • Modest efficiacy; not good against bradykinesia
  • 3rd choice after L-dopa and DA agonists
  • Side effects: sedation, mental confusion, voiding etc. (like atropine).
17
Q

Amantadine

A
  • Anti viral; increases DA release, mildly anticholinergic, NMDA receptor blocker
  • Less effective…given with L-Dopa or anticholinergics
  • only useful if L-Dopa also is effective
  • Side effects: dizziness, lethargy, sleep disturbance, peripheral edema
  • Contraindicated with CHF
18
Q

Riluzole

A
  • Inhibits NMDA channels and glutamater release; increases uptake
  • modest but genuine effects on ALS
  • increases lifespan 2-3 months